Double-image encryption by using chaos-based local pixel scrambling technique and gyrator transform

• We propose a double-image encryption algorithm by local pixel scrambling and gyrator transform.
• The system parameters serve as the keys of the encryption algorithm.
• We test the validity and security of the algorithm by numerical simulation.
• This algorithm can raise the efficiency when encrypting, storing or transmitting.

A novel double-image encryption algorithm is proposed by using chaos-based local pixel scrambling technique and gyrator transform. Two original images are first regarded as the amplitude and phase of a complex function. Arnold transform is used to scramble pixels at a local area of the complex function, where the position of the scrambled area and the Arnold transform frequency are generated by the standard map and logistic map respectively. Then the changed complex function is converted by gyrator transform. The two operations mentioned will be implemented iteratively. The system parameters in local pixel scrambling and gyrator transform serve as the keys of this encryption algorithm. Numerical simulation has been performed to test the validity and the security of the proposed encryption algorithm.